Conventionally, a toilet seat includes a body member that has a seating part that supports buttocks of a user, and a bottom plate member that has a bottom plate part that is disposed to be opposite to the seating part. For a method of manufacturing a toilet seat as described above, for example, a technique has been known for molding a body member and a bottom plate member by using a die and joining the molded body member and bottom plate member.
In a toilet seat as described above, a slight groove is generated on a joining portion between a body member and a bottom plate member. Accordingly, dirt, dust, or the like may accumulate on such a groove to spoil aesthetic appearance of a toilet seat. In recent years, a technique is proposed for pouring a molten filling material into a groove between a body member and a bottom plate member to fill and plug the groove therewith (see, for example, Japanese Laid-open Patent Publication No. 10-276935).
However, a body member and a bottom plate member may contract after molding thereof. Accordingly, in a conventional technique, for example, as a molten filling material is poured into a groove in a state where a body member and a bottom plate member are held in a die, the molten filling material may also flow into a gap between the members, a gap between the die and the members, or the like, that is generated by contraction as described above. Thus, there is room for improvement in a conventional technique as described above in that a molten filling material is appropriately poured into a groove between a body member and a bottom plate member.